Throughout our coverage of Milwaukee tools and batteries, the company has proven itself to be an uncompromising innovator. This is true not only of its tools but also of the technology behind the scenes. Milwaukee’s battery platforms have a rich history of innovation and patents and are perhaps the most important components when it comes to the function and reliability of their tools.
We batted this topic around the Pro Tool Reviews office and thought it would make for an informative article. To do this, we’d try and cover the history behind Milwaukee’s contribution to cordless lithium-ion technology. That meant going back to the brand’s initial mission and the origins of some of the company’s core tools.
Some Background and History on Milwaukee Tool
Milwaukee just celebrated its 100-year anniversary. Only a handful of tool companies share a history with as much depth and longevity in this country.
It all started in 1918 when A.H. Peterson developed the Hole-Shooter, a drill that was ahead of its time. This unit could be operated with one hand and weighed just 5 pounds. That made it far lighter than most models of the day. It was so useful that Henry Ford asked him to design it for his autoworkers.
Six years later, Albert F. Siebert purchased Peterson’s company and formed the Milwaukee Electric Tool Corporation.
In the 1930s, the organization landed substantial contracts with customers like the United States Navy. Indeed, it had come a long way since Peterson released his Hole-Shooter. It was now developing everything from electric hammers and polishers to portable grinders and sanders.
Inventing True Trademark Tools
Fast-forward to 1951. Milwaukee was going strong. Its next development involved one of its trademark (and most enduring) products: the Sawzall. It was the world’s first portable electric hacksaw to utilize a reciprocating mechanism. Possibly the most amazing thing was that it only had three moving parts! More importantly, this little saw, with its 3/4-inch stroke, let craftsmen and construction professionals cut through a variety of materials.
Over the next half century, the product line expanded, as did its list of firsts. Arguably, the company’s most important milestone was yet to come.
Milwaukee Tool has built a robust portfolio of lithium-ion battery patents that have been pivotal to their innovation and success in the power tool market. These patents cover a range of advances, from battery architecture to safety features. Together, they helped establish Milwaukee Tool as a leader in cordless power tool technology.
Key Milwaukee Lithium-ion Battery Patents and Their Impact
Milwaukee holds dozens of patents related specifically to power tools and lithium-ion battery technology. Some of those patents stand out as industry-leading, and some have even resulted in mandatory licensing fees for the use of particular types of lithium-ion batteries. Here are just a few:
US Patent 7589500B2
Method and system for battery protection
This patent, filed in 2005 and granted in 2009, focuses on improving the charging and discharging processes for batteries, particularly lithium-based ones. The patent deals with providing precise charging to avoid problems like excessive heat, overcharging, and overdischarging. This can cause irreversible damage and reduce battery life.
Milwaukee implemented several methods to protect and manage batteries. This included monitoring the temperature of the battery, transferring heat within the pack using a phase change material, and monitoring cell imbalance to ensure all cells remain evenly charged.
The proposed system can also determine and display the current charge level of the battery. This provides users with accurate information about the battery’s status. It can even interrupt the discharge current if the battery temperature gets too high, preventing damage to the pack and/or tool.
US Patent 7425816B2
Method and system for pulse charging of a lithium-based battery
This patent, filed in 2005 and granted in 2008, covers a special system that includes a battery pack and a charger. The battery pack would house several lithium-based cells within. The battery pack can check how much power each of these small batteries has by using a microcontroller inside the battery pack.
The patent also indicates that the charger would also include a microcontroller and can talk to the one in the battery pack. The charger gets information about how much power each small battery has. Then, the charger sends power to the battery pack in bursts. These bursts have two parts: a time when the battery is getting charged and a time when the charging stops. This method of charging was designed to control heat and expand the pack life.
Thermal management is crucial for maintaining safe operating temperatures, thereby preventing overheating and ensuring consistent performance. Foundational for the innovation and development of Milwaukee Tool’s RedLithium battery technology, it emphasizes efficiency and safety. This patent expires in September 2026.
US Patent 7554290B2
Lithium-based battery pack for a hand-held power tool
This patent, filed in 2007 and granted in 2009, describes a method for using a lithium-ion power tool battery pack efficiently. The battery pack has a housing that holds multiple cells, each with its own voltage. Presumably, the pack would be connected to a power tool to supply the necessary power for it to operate.
Milwaukee Tool devised a method that involves discharging one or more of the cells until its voltage matches the voltage of the other cell(s). We now call this process battery-balancing. It helps balance the power levels between all of the cells within a battery pack. This ensures the battery pack works effectively and lasts longer.
Ongoing Innovations
While some of Milwaukee Tool’s early patents have, or are approaching their expiration dates, the company continues to innovate and secure new patents. These new patents build upon the foundations laid by earlier innovations, keeping Milwaukee Tool at the forefront of lithium-ion battery technology. Recent patents focus on further improvements in energy density, thermal management, and integration with smart technologies, such as their ONE-KEY system, which allows for advanced battery management and tool customization.
Milwaukee Tool’s key lithium-ion battery patents have played a critical role in their ability to deliver high-performance, safe, and reliable power tools. These patents have not only protected their innovations but have also driven the industry forward by setting new standards for what is possible with cordless technology. As some of these foundational patents approach expiration, Milwaukee Tool’s ongoing commitment to research and development is a strong indicator that they will continue to lead the industry with cutting-edge innovation in battery technology.
Leading the Shift Toward Lithium-Ion Batteries
In 2005, Milwaukee Tool was the first manufacturer to incorporate lithium-ion battery technology into its fleet of cordless products. It was, to properly coin a popular and overused phrase, a “game-changer.” Enabling contractors and tradesmen to cut the cord more efficiently changed the industry’s productivity standards. NiCad power tools started the trend, but lithium-ion steamrolled cordless technology to a whole new level—with Milwaukee at the helm.
The new era of cordless power tools began, and the age of corded power tools started its gradual but inevitable decline. Here’s how it unfolded.
It Started with the V28 Battery Platform
Following millions of dollars in research and development, Milwaukee debuted its new technology with the launch of its V28 lithium-ion battery and corresponding line of cordless tools.
Lithium-ion was a vast improvement over nickel-cadmium (NiCd or NiCad) batteries as well as nickel metal hydride (NiMH). Specifically, the V28 battery was able to best traditional 18V nickel-cadmium in both power and runtime. Furthermore, it offered fade-free performance throughout the entire depletion time of the pack. It paved the way for more powerful corded tools to go cordless, which eventually led to the M-series of batteries.
M12 and M18 Lines – Milwaukee Innovation Expands
By 2009, Milwaukee had taken innovation to the next level, having added the M12 and M18 battery line and, around the same time, its Digital Power Management (DPM) technology. The latter made the M-series intelligent, meaning that the packs could communicate with the tool, and the tool could communicate with the battery. In addition, the battery could even interface with the charger.
DPM features included both a temperature management system and individual cell monitoring to ensure optimal temperature, charge, and discharge. It was a risky move at the time as most manufacturers were choosing whether to include electronics in either the tol or the battery. Doing both was expensive.
Milwaukee gambled on making both the battery and the tool intelligent, and that gamble seems to have been a huge win for them. This advanced communication paved the way for providing the maximum lifespan and durability for the packs. Milwaukee also introduced a side-packed design, an integrated weld frame, cell separators, and impact and vibration protection.
M28 Battery Platform
In 2010, Milwaukee forged ahead, introducing the M28 lithium-ion system. Again, the nearly century-old manufacturer had kicked things up a notch.
This series provided more power and runtime, offered enhanced durability, and enabled designers to incorporate more sophisticated electronics into the tools themselves. Additionally, the M28 platform was backward-compatible with the V28 system, which added to the flexibility and longevity of Milwaukee’s battery-powered tool fleets.
RedLithium Battery Technology Revolutionized Power Management and Delivery
That same year, Milwaukee released its RedLithium battery technology. The technology behind these packs combined advanced electronics with temperature resilience and control, resulting in more reliable and consistent output. It performed so well that it all but obsoleted the M28 platform in just a few years’ time.
The RedLithium packs delivered up to 40% more run-time, 20% more power, and about 50% more charges than conventional lithium-ion batteries. They also yielded up to 20% more torque and expanded upon the communication protocols introduced with the earlier generation of lithium-ion batteries.
Up through 2013, Milwaukee announced new M12 (12V) and M18 (18V) brushless tools, followed in 2018 by the brand’s M18 High Output batteries.
Milwaukee M18 High Output Battery Innovation and Onward
By this time, Milwaukee Tool had been in the lithium-ion game for 13 years, always looking to push the limits on their batteries’ technology and performance. An important step in the process was choosing the next-generation lithium-ion battery cells. Updated 18650, 20700, and 21700 cells were the most available and practical options.
These numbers actually refer to a battery’s measurements. For example, 18mm x 65.0mm in the case of the 18650, 21mm x 70.0mm for the 21700, and so on. Milwaukee opted for the 21700 because it offered some additional layering compared to 20700 cells. They also continued to use advanced 18650 cells for their RedLithium batteries.
21700 cells feature a 3.7-volt nominal output and a 5,000 mAh capacity. (The higher the mAh, the longer it can go between charges.)
With M18 High Output batteries, the tradeoff was a larger battery pack (made up of larger individual cells) to gain extended runtime and/or power. Additionally, Milwaukee engineers incorporated thicker wires and better connections to reduce resistance, thus boosting the power transfer efficiency.
What they wound up with was a more powerful pack that also ran 50% cooler than standard RedLithium.
The net result was tools with more muscle, like the M18 Fuel Super Sawzall and the Milwaukee 2732 circular saw, to name just two.
Milwaukee MX Fuel Battery Innovation
In terms of the big picture, Milwaukee Tool hit the ground running in 1924 and hasn’t stopped since. So, what came next? Tackling cordless equipment.
By this time, battery-powered tools had proven more powerful than their corded counterparts. With the exception of runtime (and rapid chargers have whittled that concern to near non-existence), battery-powered tools ruled the day.
However, one segment of the industry remained elusive: power equipment. In an effort to break into this segment of the market, Milwaukee released its MX Fuel platform. MX Fuel provided the sheer Watt-hour capacity required for products like demo hammers, power cutters, core drilling rigs, concrete vibrators, screeds, and more.
In short, Milwaukee took the concrete tool world by storm. They added battery-powered solutions that offered acceptable runtimes and reduced some of the hassles and dangers associated with corded or pneumatic tools.
M18 Forge and MX Fuel Forge Batteries
Following the 2019 release of MX FUEL tools and batteries, Milwaukee continued in earnest on its next innovative battery platform. At Pipeline 2023, the company introduced Milwaukee FORGE batteries for its M18 and MX Fuel lines. It wasn’t long before we got our hands on these new batteries and began realizing their benefits.
Milwaukee FORGE batteries introduced both tabless and pouch cell technology. The tabless battery design greatly reduces the resistance of the pack’s cells. The overall result is lower electrical impedance between the cell and the motor. As I mentioned earlier, lower resistance (measured in ohms) facilitates a more efficient energy transfer, producing less heat. This lets the tool draw power more rapidly and to a greater extent without the pack hearing up as quickly.
Pouch cell batteries deliver more power in a smaller size with similar but different efficiency gains. This design has significantly less electrical resistance, which ultimately results in greater efficiency and less heat transfer than you see with traditional 18650 or even 21700 battery cells.
It’s All [Heat Management] Nowadays
I sat down to talk with Zafir Faroouque, group manager of product marketing, about heat management. It all seems to come down to our old friend impedance. “The game here is cutting resistance,” Zafir says. “The lower you can reduce the impedance, the less heat you’re generating when you’re working or charging a battery.”
Less heat means better efficiency of energy, which ultimately leads to longer runtimes.
“We get as close to zero [impedance] as possible by using higher quality metals and improving the contact between the tool terminal and the battery terminal to make sure there’s a solid connection,” he explains. “All of this helps keep the battery cool during discharge.”
According to Faroouque, many don’t realize that when the battery is put on the charger, it’s not getting a break from work. Because you’re transferring power back into the pack, it generates heat and consequently puts a load on the unit.
And that brings us to charging.
How Milwaukee Tool is Addressing Charging Solutions
Milwaukee manages the challenge of charging with its proprietary Cool Cycle Active Cooling System. The brand’s MX FUEL Super Charger uses this technology. When the battery is docked onto the charger, the system forces air across the cells. This prepares them for charging, whereas a typical charger would simply have to monitor the pack and wait until the temperature reaches a state where the pack can be safely charged.
Depending on the battery you’re using, you’ll see charge times as short as 45 minutes. Of course, like cookies, fast-charging is a “sometimes treat.” Every time you charge a battery using rapid technology you put stress on the pack. Whenever possible, use a standard charger and you’ll get the most like out of your battery packs for the long haul.
Milwaukee is also addressing the issue of onsite charging for landscapers and others who need tools charged overnight or stored in trailers. In all cases, the developments involve sophisticated power management solutions coupled with chargers that work solo or when organized into groups. We plan a separate article to go over that in greater detail as it warrants the time and attention.
What’s It All Mean?
Battery technology and cordless power tools have undoubtedly changed the world. Milwaukee’s efforts (well-documented by their many patents) have certainly played a crucial role in revolutionizing both tool design and how we use cordless power tools in the field. The story of Milwaukee’s journey through the battery landscape shows us that the difficult march forward never stops.
Milwaukee’s innovations call to mind a line from A League of Their Own, where Jimmy Dugan (played by Tom Hanks) states his take on another game—baseball.
“It’s supposed to be hard. If it wasn’t hard, everyone would do it. The hard… is what makes it great.”
I think that speaks to Milwaukee’s rich history of innovation in lithium-ion batteries.
